I was raised in a temperate climate — New Zealand, to be precise — but it didn't take me long to grasp the absolute, primal importance of coats in much of North America. (Moving to Minnesota in January will teach you the value of a proper winter coat in, oh, about 15 seconds. Which is about the time it took the parts of my wet hair not covered by my hat to freeze one morning, oh happy Midwestern memories!) The problem is, as any card-carrying member of what Garrison Keillor called God's frozen people knows, is that the most stylish coats tend to be the least warm. Bunchy ski-wear made with Gore-Tex and studded with elastic drawstrings isn't really cute — and fuck me are those things expensive — but it does a much better job of keeping you warm than your average lined wool-blend shell from Old Navy. But if you're nonetheless drawn, for reasons of aesthetic preference or the necessity of maintaining a "professional" appearance, to non-sporty coats, there are some ways to trick them out. With basic sewing skills you can take any plain old coat and turn it into a piece of performance sportswear — on the inside.

Click any photo in this post to enlarge. For this DIY, you will need, clockwise from top: 1) A coat. I'm using a secondhand camel coat I inherited from a family friend. I like it, and I wear it, but it's never been the warmest. 2) A pair of sewing scissors. 3) Straight pins for machine sewing and needles for hand-sewing. 4) A spool of thread in a color that matches your coat. 5) Two socks (they don't even have to match). You will also need an iron and ironing board, a sewing machine, and a spool of heavy-duty buttonhole thread, not pictured.

What we're going to do is turn our socks into comfortable, soft, warm ribbed wrist bands that we're going to sew into the lining of the coat, near the sleeve hem. You know that feeling when an icy finger of winter wind shoots past the top of your glove and up your sleeve? Hidden ribbed cuffs put a stop to that. You can buy ribbed cuffs ready-made from a sewing or notions store, but you can also make them out of recycled socks — which is my preferred method, because I always have a few old, holey, and/or orphaned socks lying around. The first step is to cut off and discard the foot part of the sock. All you need is the straight part above the ankle.

Trim so that your two socks are the same length, then fold each sock in half, purl side in and knit side out, to make your ribbed cuff. Aim for cuffs of about 2.5-3.5" in length, so you have enough room for a seam allowance.

Fold up the sleeves of your coat at or just below the elbow, to expose the lining. Measure the cuff against the lining. We're going to cut around the lining to create a seam where we're going to attach the cuff; you want this seam to be high enough that the cuff will stay tucked away, hidden by the sleeve itself when you wear the coat, but low enough that the cuff will cover your wrist.

Make sure to add a seam allowance, then make a slice in the lining with your scissors. Cut as straight as you can all the way around. (It doesn't have to be totally perfect.)

Then fold down the newly cut piece of lining, and unpick it from the hem of the coat sleeve. If you have buttons on your sleeve, you may have to cut one or more of them off for now in order to fully separate the lower part of the lining. Once you have it totally unpicked from the sleeve, give this piece a quick press with your iron. Linings have a way of bunching and getting all wrinkly near the wrist, and you want yours to be flat for easy sewing. You now have two pieces of lining for the sleeve: the upper sleeve is still attached to the coat, and the lower sleeve is separate.

Now, observant DIYers will be aware by now that what we're doing is essentially adding a seam to an existing lining. With 3/8" seam allowances, that's the equivalent of shortening our sleeve lining by 6/8", which in a fashion fabric would not be a negligible amount. But linings are always cut more generously than fashion fabrics; manufacturers tend to err on the side of more wearing ease. So we're really just taking a little away from the excess. If you have a coat to which you want to add ribbed cuffs, but you find the lining it too skimpy to accomodate them, here is where you should cut the lower sleeve lining piece from a bolt of lining of your own, and use it instead of the lower sleeve piece from your coat's existing lining. Does that make sense? It hardly matters whether you have a new kind of lining, then a cuff, then the original lining going up your sleeve — it's the inside of a sleeve. Nobody's going to be looking at it. Now, take the lower sleeve lining piece, and pin it to the raw edge of the ribbed cuff.

Use a stretch stitch to sew the cuff to the lower lining, and pull the cuff out taught as you make your way around to prevent bunching.

When you're done, turn the pieces you just sewed inside out, so that the ribbed cuff is on the outside.

Slip the piece you just sewed into the upper sleeve lining, match up the raw edges, pin, and sew. Again, use a stretch stitch and stretch out the cuff as you sew to prevent bunching.

Unfold the lining. Ta-da: Your cuff is now securely attached to your lining.

Here's what it looks like to stare down the barrel of your new sleeve.

The last step is to re-attach the lower edge of the lining to your sleeve hem. Use a blind-stitch or whatever stitch you're most comfortable with for this part.

I lied! The actual last step is to re-attach any buttons you had to take off before. Sewing a button is easy: just load up a needle with buttonhole thread, and make a couple passes through the holes. Allow the thread to remain a bit loose, so the button will have some clearance, but keep the tension consistently loose, if you know what I mean.

On your last pass, wrap the thread around the button shank a few times, or until you almost run out of thread. Then push your needle through to the wrong side, and knot securely.

Here's the finished cuff. Not bad.

And there, hidden inside, is a nice, warm secret.

Some other winter coat warmifying tips?

Double-breasted coats are warmer than single-breasted.

If you really want to keep warm, consider adding an interlining to your coat. A thin wool flannel or — the ultimate wind-stopper — a leather like chamois works wonders. You don't have to interline the whole coat: cutting a piece of flannel or chamois to cover the back, from neck to hips, will suffice. Slide that piece between the lining and the fashion fabric, and hand-stitch it to the fashion fabric's seam allowances at the shoulder and down the sides to secure. You often see interlinings on vintage coats, so if you're thrift shopping, slip your hand up the back to check. I have a double-breasted black wool coat from the '70s with a flannel and a chamois interlining, to which I added hidden ribbed cuffs, and I spend about six weeks of every year rejoicing in its very existence. Because it is the warmest coat ever. It cost me $66.50 plus a whopping $20 shipping and handling on eBay — a fortune, given I was a student — but I've never regretted it.

Sleeves are a primary vector for freezing wind to gain purchase on your person, and you can prevent that by adding cuffs as explained above. But what about wind that blows up your coat? Style permitting, you can take inspiration from ski jackets and add a hidden drawstring to your coat lining at your waist. Otherwise, you can add belt loops (thread chains in heavy-duty buttonhole thread will suffice, or a grosgrain ribbon) to the outside of your coat at the waist, and use a sash belt. The belt doesn't have to match the coat. Once your coat is cinched in at the waist, your back's vulnerability to icy wind will be markedly lessened.

This isn't technically a warming tip, but it is a great general coat tune-up tip. Machine-sewn buttons on coats are bad news, and they tend to pop off at the most inopportune times. There's nothing like being unable to button your coat all the way in a snowstorm — and it's almost as annoying to have to go to a notions store and buy all new buttons for your coat because one came off and got lost. If you have a coat you love but it has machine-sewn buttons, take them all off and re-sew them by hand. You'll feel more secure (and your coat will look more expensive and last longer).